The synthesis of methanol ((CH.sub.3 OH) from a synthesis gas consisting predominantly of carbon monoxide (CO) and hydrogen (H.sub.2) can be carried out ctalytically on a wide variety of catalysts in particulate, granular or other form in a reactor which comprises a housing containing a packing of the catalyst, cooling tubes spaced apart within the catalyst body, and means for passing a coolant (e.g. water) through the cooling tubes and for passing the gas mixture generally axially through the packing.
Since the methanol-synthesis reaction is highly exothermic, the use of cooling tubes in spaced-apart relationship within and in intimate contact with the catalyst body is important to prevent overheating of the synthesis gas and the reaction product entrained therein and the catalyst material as well.
It is known to provide the cooling tubes so that they run generally transversely to the direction of gas flow, e.g. in the form of layers of helical coils surrounding a core tube so that the turns are generally transverse to the synthesis gas flow direction.
A reactor of this type is described in German Open Application DE-OS No. 25 04 343. The cooling-tube arrangement shown and described in this publication prevents the exothermally generated heat of the reaction from shifting the reaction kinetics to the point that undesired reaction products are produced.
Further investigations with reactors of the aforedescribed type have shown that they are not always effective in abstracting the exothermally generated heat to preclude the formation of undesired products or to ensure a high efficiency in the production of methanol.
It appears that the hot reaction products are not always cooled sufficiently and that the reaction cannot be properly controlled merely by providing large numbers of tubes, tube layers or high coolant flow rates. To date, the only effective way of solving the problem has been to overdimension the reactor which increases the quantity of catalyst material for a given volume rate of flow of the synthesis gas and results in increased process operating costs as well as increased capital expenditure for the reactor. Even these expedients are not always satisfactory.